<template>
    <div>
        <router-link
         tag="div"
         to="/"
        class="header-abs"
        v-show="showAbs"
        >
            <div class="iconfont header-abs-back">&#xe624;</div>
        </router-link>
        <div class="header-fixed"
         v-show="!showAbs"
         :style="opacityStyle"
        >
            <router-link to="/">
                <div class="iconfont  header-fixed-back">&#xe624;</div>
            </router-link>
            景点详情
        </div>
    </div>
</template>
<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {opacity}
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }

  },
  mounted  () {
    window.addEventListener('scroll', this.handleScroll)
  },
  unmounted () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}

</script>
<style lang="stylus" scoped>
  @import '~@/assets/styles/varibles.styl'
    .header-abs
        position absolute
        left .2rem
        top .2rem
        width .8rem
        height .8rem
        line-height .8rem
        border-radius .4rem
        text-align center
        background rgba(0,0,0,.8)
        .header-abs-back
            color #fff
            font-size .4rem
       .header-fixed
        z-index 2
        position fixed
        top  0
        left 0
        right 0
        height $headerHeight
        line-height $headerHeight
        text-align center
        color #fff
        background $bgColor
        font-size .32rem
        .header-fixed-back
            position absolute
            top 0
            left  0
            width .64rem
            text-align center
            font-size .4rem
            color #fff

</style>
